System of control.



vR. E. HELLMUND.

SYSTEM OF CONTROL.

APPLICATION FILED APR. 29. 1915.

1,287,016. Patented Dec.10, 1918.

5L1 17S, ISL L 'L WITNESSES: INVENTOR J M41424 Rut/ 4) [He/mum R. E. HELLMUND.

SYSTEM OF CONTROL.

APPLICATION man APR.29, 1915.

1,287,016. Patented Dec. 10, 1918.

2 SHEETS-SHEET 2.

WITNESSES t I INVENTOR 5/ Rude/fEf/d/Mund UNITED STATES PATENT OFFICE.

RUDOLF E/HELLMUND, or PITTSBURGH, PENNSYLVANIA, ASSIGNOR r0 WESTING- HOUSE ELECTRIC AND MANUFACTURING COMPANY, A conronA'rIo or PENN- SYLVANIA.

sYsrEi/i or CONTROL.

Specification of Letters Patent.

Patented Dec. 10, 1918.

Application filed April 29, 1915. Serial No. 24,739.

To all whom it may concern:

Be it known that I, RUDOLF E. HELLMUND, a subject of the Emperor of Germany and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Systems of Control, of which the following is a specification.

My invention relates to control systems for alternating-current dynamo electric machines of the commutating type, and it has for its object to provide means for the definite adjustment of the field of the machine under control, both as to strength and as to phase relation, when the machine is operating as a motor or is regenerating and supplying energy to a circuit, as is customary, for example, in railway work.

Referring to the accompanying drawing, Figure 1 is a diagrammatic View of a dynamo-electric machine of the commutating type provided with attendant exciting and control circuits constructed in accordance with my invention; Fig. 2 is a diagrammatic view of a modified form of the circuits of Fig. 1 arranged for the phase control of the main motor field current, Fig. 3 is a chart indicating the sequence of switch operation in the circuit of Fig. 1, during'both regeneration and acceleration, and Fig. 4 and Fig. 5 are simplified views showing a sequence of connections.

In the operation of single-phase alternating current railway systems, it has been suggested, as disclosed in U. S. Patent, #977,641, granted December 6, 1910 to the Vvestinghouse Electric & Manufacturing Company on an application filed by Benjamin G. Lamme, to excite the main field winding of a commutator motor with current of displaced phase for regenerative operation. It is frequently desirable to separately excite the main field windin s of commutating machines during motor operation in order to obtain shunt speed characteristics and it is therefore customary to use the regenerating exciting machine during motor operation. If an exciting machine is used continuously in this manner, it must be of considerable size and weight, and I have found that a speed characteristic approaching that of a shunt machine may be obtained by supplying a major ortion of the main field excitation by a series connection and by supplementing said series current by current of displaced phase obtained from the auxiliary machine. In this manner, the size and Weight of the exciter may be much reduced and substantially equivalent results obtained.

Hitherto, alternating-current commutator motors have either had series operating characteristics, or, if shunt excited, they have generally not been self-starting. The .Winter-Eichberg motor provides the nearest approximation to the characteristics of a direct-current shunt motor but even here the field varies in accordance with the speed. By my invention, I provide a self-starting alternating-current commutator motor having shunt operating characteristics, adapted to a wide range of usefulness in the arts.

Referring to Fig. 1, 16 is any suitable source of alternating current, such, for example, as the secondary winding of a trans former provided with a core 17. The secondary windinp: 16 is provided with a pluralitv of voltage taps connected, respectively to switching devices 1, 4, 6, 7, 9, 10, 12 and 14. A dynamo-electric machine of the commutating type that is-shown at 18, is provided with an armature 19, a main field winding 20 and a cross field winding 21. A phase converter is shown at 22 and comprises a rotor 23, a main field winding 24 and a cross field winding 25. The machine 23 may be driven by any suitable means, such, for example, as a variable-speed induction motor 26 connected to a separate secondary winding 33 of the core member 17 by suitable wires 27. The speed of the induction motor 26 may be adjusted by any suitable means, such, for example, as an adjustable rheostat 28 connected in the rotor winding thereof through suitable slip rings. Any other suitable variable-speed motor, such, for example, as one of the series commutating type, may be provided in place of the variable-speed induction motor 26, and a phase converter of any suitable type may be substituted for repulsion machine shown at 22.

The electromotive force applied to the armature winding 19 may be adjusted by the operation of the switches 4, 5 and 6 and a preventive resistance member 29, and the voltage applied to the cross field winding 21 may be adjusted by means of switches 7 8, 9 and a preventive resistance member 30, in a manner well known in the art. In

a similar manner, the voltage applied to a main field winding 21 may be adjusted by suitable manipulation of the switches 10, 11, 12, 13 and 11 and preventive resistance devices 31 and 32.

Upon starting the vehicle, as indicated in the first accelerating position in the chart of Fig. 3, the switches 1, 3, 4, 7 10, 11 and 15 are closed. Under these conditions, the armature winding 19 and the main field winding 20 are connected in series relation to receive a relatively small voltage from the source 16. The cross field winding 21 is connected to receive a relatively small voltage from the source 16 and to operate upon the armature 19 in accordance with the well known doubly-fed connection. The main field winding 24 is excited to a small degree, and the cross field winding 25, acting as a generating winding is supplying current to the main field winding 20 and assisting in the excitation thereof. The voltage supplied by the generating winding 25 to the main field winding 20 is next increased by suitable manipulation of the switches 10, 11, 12, 13 and 14 and the preventive resistance members 31 and 32 until, at the fifth accelerating position, the exciter 22 is delivering a maximum voltage. The speed of the machine 18 is then increased by suitably manipulating the voltages supplied to the armature .winding 19, the main field winding 20 and the cross field winding 21, respectively, through the operation of switches 4 to 9, inclusive, and of the preventive resistance members 29 and 30. From the sixth to the ninth accelerating positions, inclusive, the excitation of the main field winding 20 directly from the source 16 is of such magnitude and phase relation that it is unnecessary to employ the separate exciting machine 22, although said machine could obviously be employed if desired. When a comparatively high speed of the armature 19 is obtained, for example, at the tenth accelerating position, it is desirable to again provide a shunt operating characteristic. Exciting current from the machine 22 is therefore supplied for the last three accelerating positions. I have provided this reconnection by suitable operation of the control switches, but, if it is desired to make 'this reconnect-ion purely automatic, it may readily be done, without involving invention, by the use of any of the well known automatic devices, such, for example, as a centrifugal switch or a current relay.

\Vhen it is desired to supply energy from the machine 18 to the source 16, as, for example, when the vehicle is coasting, switches, 1,

2, 3, 5, 6, 8, 9, 10 and 11 are closed as shown.

under the first regenerating position in Fig. 3. Comparatively large portiohs of the source 16 are embraced by the connections of the windings of the machine 18, and a relatively small voltage is supplied by said machine because the excitation furnished by the machine 22 to the main field Winding 20 is at a minimum. A small amount of energy is therefore returned to the source 16. The portion of the source 16 embraced between the connections ofthe winding of the machine 18 is then gradually decreased, while the excitation furnished by the machine 22 is gradually increased, with the result that the amount of energy returned to the source is increased in a uniform manner, and the braking effect on the vehicle is smooth and free from unpleasant jolt.

Referring to the form of my invention shown in Fig. 2, the essential connections are the same as shown in Fig. 1, with the exception that the main field winding 20 and the generating winding 25 are connected in series relation with each other and with a portion of the source, in order that the resultant voltage brought about by the vector addition of the voltages of the winding 25 and of the portion of the source 16 may have any desired value and phase relation with respect to the voltage of the source, in the manner described in my copending application, Serial No. 19,460, filed Apr. 6, 1915, and assigned to the Westinghouse Electric & Manufacturing Company.

Throughout this case, the exciter machine has been described as supplying energy to the main field winding 20 but, when it is desired that the excitation of said winding shall have a small value, the voltage relations may be such that the exciter machine is deriving energy from the connections of the winding 20, rather than supplying energy thereto.

While I have shown my invention in two distinct modifications, it is obvious to those skilled in the art that it is susceptible of various additional minor changes without departing from the spirit thereof and I accordingly desire that no restrictions shall 110 be placed thereon except those that are imposed by the prior art or are specifically set forth in the appended claims.

I claim as my invention:

1. The method of operating a dynaino- 115 electric machine of the series commutating type provided with a main and with a cross field Winding and connected to a main source of alternating current of fluctuating voltage, which comprises exciting the main 120 field winding thereof from said main source when said machine is operating as a motor and regulating said excitation by current flow from an auxiliary source of like frequency to the main source but of adjustable 125 voltage and displaced phase relation with respect thereto at low and at high motor speeds, and adjusting the speed of the motor both by varying the voltage applied to the armature and by varying the voltage sup- 130 plied from said auxiliary source, and exciting said main field winding from said auxiliary sourcewhen the said machine is operat ing as a generator and supplying power to said main source, and adjusting the amount of power supplied to said source by varying the voltage supplied by said auxiliary source and by varying the connections of the armature winding to the main source.

2. The method of accelerating an alternating-current motor of the commutator type provided with both inducing and magnetizing-field windings, said motor being associated with a main source of alternating current and provided with means whereby it may be connected to said source for doubly-fed operation with adjustable voltage upon the inducing-field winding and upon the armature and magnetizing-field windings, said motor being further associated with means arranged to, at will, impress a variable dephased electromotive force upon the magnetizing-field winding thereof which comprises initially connecting said motor for doubly-fed operation with a relatively small impressed voltage from said main source upon the windings thereof and supplementing the excitation of said magnetizing-field winding by a relatively small component of dephased electromotive force, and thereafter increasing said dephased component.

3. The method of accelerating an alternating-current motor of the commutator type provided with both inducing and magnetizing-field windings, said motor being associated with a main source of alternating current and provided with means whereby it may be connected to said source for doubly-fed operation -with adjustable voltage upon the inducing-field winding and upon the armature and magnetizing-field wind- 'ings, said motor'being further associated with means arranged to, at will, impress a variable dephased electromotive force upon the magnetizing field winding thereof which comprises initially connecting said motor for doubly-fed operation with a relatively small impressed voltage from said main source upon the windings thereof and supplementing the excitation of said magnetizing-field winding by a relatively small component of dephased electromotive force, thereafter increasing said dephased component and finally removing said dephased exciting component and raising the voltage applied to said armature and magnetizingfield winding from said mainsource.

4. The method of accelerating an alternating-current motor of the commutator type provided with both inducing and magnetizing-field windings, said motor being associated with a main source of alternating current and provided with means whereby it may be connected to said source for doubly-fed operation with adjustable voltage upon the inducing-field winding and upon the armature and magnetizing-field windings, said motor being further associated with means arranged to, at will, impress a variable dephased electromotive force upon the magnetizing-field winding thereof which comprises initially connecting said motor for doubly-fed operation with a relatively small impressed voltage from said main source upon the windings thereof and supplementing the excitation of said magnetizing-field winding by a relatively small component of dephased electromotive force, thereafter increasing said dephased component, removing said dephased exciting component and raising the voltage applied to said armature and magnetizing-field winding from'said main source, and finally restoring said dephased exciting component.

5. The method of accelerating an alternating-current motor of the commutator type provided withboth inducing and magnetizing-field windings, said motor being associated with a main source of alternating current and provided with means whereby it may be connected to said source for doubly-fed operation with adjustable 'voltage upon the inducing-field winding and upon thearmature and magnetizingfield windings, said motor being further associated with means arranged to, at will, impress a variable dephased electromotive force upon the magnetizing-field winding thereof'which comprises initially connecting said motor for doubly-fed operation with a relatively small impressed voltage from said main source upon the windings thereof and supplementing the excitation of said magnetizing-field winding by a relatively small component of dephased'electromotive force, thereafter increasing said dephased component, removing said dephased exciting component and raising the voltage applied to said armature and magnetizingfield winding from said main source, restoring said dephased exciting component with relatively large magnitude, and finally reducing said dephased exciting component.

6. The method of accelerating an alternating-current motor of the commutator type provided with windings carrying currents dependent upon the load and with magnetizing-field conductors connected in series relation with one of said windings, said motor being associated with a main source of alternating current and also with means arranged to, at will, impress an adjustable dephased electromotive force upon said magnetizing conductors, which comprises initially impressing upon said motor a relatively small electromotive force from said source, adjusting the dephased electromotive force impressed upon the magnetizing conductors to a relatively small value,

and thereafter increasing both the dephased electromotive force and also that impressed from the source.

7. The method of accelerating an alternating-current motor of the commutator type providing with windings carrying currents dependent upon the load and with magnetizing field conductors connected in series relation with one of said windings, said motor being associated with a main source of alternating current and also with means arranged to, at will, impress an adjustable dephased electromotive force upon saidmagnetizing conductors, which comprises initially impressing upon said motor a relatively small electromotive force from said source, adjusting the field excitation by impressing the dephased electromotive force upon the magnetizing conductors, and thereafter disconnecting said dephasing means to efi'ect excitation dependent upon the load current during certain subsequent periods of acceleration.

8. The method of accelerating an alternating-current motor of the commutator type provided with windings carrying currentsdependent upon the load and with magnetizing field conductors connected in series relation with one of said windings,

a relatively small electromotive force from I said source, adjusting the field excitation by impressing the dephased electromotive force upon the magnetizing conductors during certain low-speed and certain higher-speed operating conditions, and disconnecting the dephasing means to effect excitation dependent upon the load current during certain intermediate speed periods of acceleration.

In testimony whereof, I have hereunto subscribed my name this 23rd day of April, 1915.

RUDOLF E. HELLMUND. 

